As the techniques for the miniaturization of semiconductor devices have recently been advanced and as the semiconductor devices have increasingly been manufactured so as to have three-dimensional structures, it has increasingly been needed to form a silicide film on the bottom and/or side walls of trench and hole patterns, which have been formed on a substrate and there has also been an increasing demand for the development of a technique which can ensure the achievement of high coverage characteristics (the step coverage) with respect to these bottom and/or side walls of the trench and hole patterns.
As a metallic material used for forming such a silicide film, there have in general been used, for instance, Ti, Co and Ni. In this respect, the sputtering technique has conventionally been used for the deposition of films of these metals, but this technique has been found to be insufficient in the coverage characteristics of such films used for covering the bottom and/or side walls of the trench and hole patterns with the recent progress of the miniaturization technology and accordingly, it would be difficult for this technique to cope with the foregoing situations.
For this reason, there has been developed a CVD technique in which a film is formed while a metal compound is introduced into a film-forming system after the compound is converted into its gaseous state. Nevertheless, this CVD technique suffers from a variety of problems as will be described below, since an organometal compound is used as a metal-containing gaseous precursor in this CVD technique: A large quantity of impurities such as C, N and O are incorporated into the resulting film; even if subjecting the film to a heat treatment for the conversion thereof into a silicide, the silicide-forming reaction is inhibited by the action of these impurities; and it is thus quite difficult to form a silicide film from the metal film prepared according to this CVD technique as compared with the metal film prepared according to the conventional sputtering technique.
In this respect, a silicide film can be formed simply by the film-forming step according to the CVD technique at a high temperature (for instance, 500° C.) which permits the direct preparation of a silicide film, but it would be quite difficult for this CVD technique to form an excellent silicide interface required for the semiconductor device or the like. For instance, a problem arises such that. in the case of Ni, the NiSi film can form a good interface having a low resistance, but an NiSi2 film is formed when the film-forming step is carried out at a high temperature and any flat interface having a low resistance cannot be formed. In addition, in such a film-forming step at a high temperature, further problems arise such that although the film-forming rate is increased, the rate may be limited to undesirable level since the flow rate of the precursor serves as a rate-determining step and the coverage characteristics of the film are deteriorated.
Moreover, when a semiconductor device is manufactured, a hydrogen-annealing treatment has been carried out (see, for instance, Patent Document 1 specified below) for the purposes of, for instance, the removal of the oxygen present in a conductive metal film, the removal of the impurities present in a conductive metal film (such as a Cu film) to thus improve the electrical characteristics of the metal film, and the improvement of the adhesion of the primary film to a Cu film.